1=head1 NAME 2 3/etc/xen/xl.conf - XL Global/Host Configuration 4 5=head1 DESCRIPTION 6 7The F<xl.conf> file allows configuration of hostwide C<xl> toolstack 8options. 9 10For details of per-domain configuration options please see 11L<xl.cfg(5)>. 12 13=head1 SYNTAX 14 15The config file consists of a series of C<KEY=VALUE> pairs. 16 17A value C<VALUE> is one of: 18 19=over 4 20 21=item B<"STRING"> 22 23A string, surrounded by either single or double quotes. 24 25=item B<NUMBER> 26 27A number, in either decimal, octal (using a C<0> prefix) or 28hexadecimal (using an C<0x> prefix). 29 30=item B<BOOLEAN> 31 32A C<NUMBER> interpreted as C<False> (C<0>) or C<True> (any other 33value). 34 35=item B<[ VALUE, VALUE, ... ]> 36 37A list of C<VALUES> of the above types. Lists are homogeneous and are 38not nested. 39 40=back 41 42The semantics of each C<KEY> defines which form of C<VALUE> is required. 43 44=head1 OPTIONS 45 46=over 4 47 48=item B<autoballoon="off"|"on"|"auto"> 49 50If set to "on" then C<xl> will automatically reduce the amount of 51memory assigned to domain 0 in order to free memory for new domains. 52 53If set to "off" then C<xl> will not automatically reduce the amount of 54domain 0 memory. 55 56If set to "auto" then auto-ballooning will be disabled if the 57C<dom0_mem> option was provided on the Xen command line. 58 59You are strongly recommended to set this to C<"off"> (or C<"auto">) if 60you use the C<dom0_mem> hypervisor command line to reduce the amount 61of memory given to domain 0 by default. 62 63Default: C<"auto"> 64 65=item B<run_hotplug_scripts=BOOLEAN> 66 67If disabled hotplug scripts will be called from udev, as it used to 68be in the previous releases. With the default option, hotplug scripts 69will be launched by xl directly. 70 71Default: C<1> 72 73=item B<lockfile="PATH"> 74 75Sets the path to the lock file used by xl to serialise certain 76operations (primarily domain creation). 77 78Default: C</var/lock/xl> 79 80=item B<max_grant_frames=NUMBER> 81 82Sets the default value for the C<max_grant_frames> domain config value. 83 84Default: C<32> on hosts up to 16TB of memory, C<64> on hosts larger than 16TB 85 86=item B<max_maptrack_frames=NUMBER> 87 88Sets the default value for the C<max_maptrack_frames> domain config value. 89 90Default: C<1024> 91 92=item B<vif.default.script="PATH"> 93 94Configures the default hotplug script used by virtual network devices. 95 96The old B<vifscript> option is deprecated and should not be used. 97 98Default: C</etc/xen/scripts/vif-bridge> 99 100=item B<vif.default.bridge="NAME"> 101 102Configures the default bridge to set for virtual network devices. 103 104The old B<defaultbridge> option is deprecated and should not be used. 105 106Default: C<xenbr0> 107 108=item B<vif.default.backend="NAME"> 109 110Configures the default backend to set for virtual network devices. 111 112Default: C<0> 113 114=item B<vif.default.gatewaydev="NAME"> 115 116Configures the default gateway device to set for virtual network devices. 117 118Default: C<None> 119 120=item B<remus.default.netbufscript="PATH"> 121 122Configures the default script used by Remus to setup network buffering. 123 124Default: C</etc/xen/scripts/remus-netbuf-setup> 125 126=item B<colo.default.proxyscript="PATH"> 127 128Configures the default script used by COLO to setup colo-proxy. 129 130Default: C</etc/xen/scripts/colo-proxy-setup> 131 132=item B<output_format="json|sxp"> 133 134Configures the default output format used by xl when printing "machine 135readable" information. The default is to use the C<JSON> 136L<http://www.json.org/> syntax. However for compatibility with the 137previous C<xm> toolstack this can be configured to use the old C<SXP> 138(S-Expression-like) syntax instead. 139 140Default: C<json> 141 142=item B<blkdev_start="NAME"> 143 144Configures the name of the first block device to be used for temporary 145block device allocations by the toolstack. 146The default choice is "xvda". 147 148=item B<claim_mode=BOOLEAN> 149 150If this option is enabled then when a guest is created there will be an 151guarantee that there is memory available for the guest. This is an 152particularly acute problem on hosts with memory over-provisioned guests 153that use tmem and have self-balloon enabled (which is the default 154option). The self-balloon mechanism can deflate/inflate the balloon 155quickly and the amount of free memory (which C<xl info> can show) is 156stale the moment it is printed. When claim is enabled a reservation for 157the amount of memory (see 'memory' in xl.conf(5)) is set, which is then 158reduced as the domain's memory is populated and eventually reaches zero. 159The free memory in C<xl info> is the combination of the hypervisor's 160free heap memory minus the outstanding claims value. 161 162If the reservation cannot be meet the guest creation fails immediately 163instead of taking seconds/minutes (depending on the size of the guest) 164while the guest is populated. 165 166Note that to enable tmem type guests, one needs to provide C<tmem> on the 167Xen hypervisor argument and as well on the Linux kernel command line. 168 169Default: C<1> 170 171=over 4 172 173=item C<0> 174 175No claim is made. Memory population during guest creation will be 176attempted as normal and may fail due to memory exhaustion. 177 178=item C<1> 179 180Normal memory and freeable pool of ephemeral pages (tmem) is used when 181calculating whether there is enough memory free to launch a guest. 182This guarantees immediate feedback whether the guest can be launched due 183to memory exhaustion (which can take a long time to find out if launching 184massively huge guests). 185 186=back 187 188=back 189 190=head1 SEE ALSO 191 192=over 4 193 194=item L<xl(1)> 195 196=item L<xl.cfg(5)> 197 198=item http://www.json.org/ 199 200=back 201